1. Field of the Invention
The present invention is broadly concerned with supplemental gas assemblies such as supplemental oxygen units typically used in aircraft for supplying supplemental oxygen to aircraft crew in the event of a cabin depressurization or other emergency. More particularly, the invention is concerned with such assemblies wherein a self-elongating gas hose assembly is employed which, when pressurized, axially expands to a significant extent. This gives the user a relatively long effective hose length, while avoiding the problems of handling and stowage typical with conventional hoses.
2. Description of the Prior Art
During the course of aircraft operation, pilots, navigation officers and other crew personnel, may need supplemental gas (e.g., oxygen) to provide protection from smoke from onboard fires and other possible airborne eye and lung irritants which may enter the crew compartment. There is a requirement in the commercial aviation industry that crew masks be capable of donning in five seconds or less. The provision of crew mask assemblies is sensitive to both the quick-donning requirements and the very limited space and volume available in aircraft flight decks.
The donning issue has been responded to by provision of crew oxygen masks having inflatable harnesses. In such designs (see U.S. Pat. Nos. 4,915,106 and 5,664,566), the harness straps expand upon introduction of pressurized gas to assume an enlarged configuration permitting easy donning. When vented, however, these harness assemblies contract and engage the wearer""s head to firmly hold the mask in place.
In recent years, available flight deck space has become even more precious, leading to efforts to reduce the volume of components. However, very little reduction in mask stowage box volume has been achieved, owing to the fact that the oxygen delivery hoses coupled with the mask must be of a certain minimum length to allow and facilitate crew use. That is, these stowage boxes, because they must receive a relatively long length of hose, cannot be readily reduced in size.
There is accordingly a need in the art for improved supplemental gas assemblies which can be made in a more compact design, while still achieving the degree of utility and rapid donning characteristics required for crew oxygen equipment.
The present invention overcomes the problems outlined above and provides supplemental gas (e.g., oxygen) assemblies including a mask adapted to fit over at least the nose and mouth of a wearer, with a flexible hose coupled with the mask and a source of supplemental gas; at least a portion of the mask and the hose are received within a stowage box. In accordance with the invention, the hose assembly comprises a length-expandable hose which, when a user grasps the mask and pulls it from the stowage box, will inflate and axially expand to a deployed length greater than the relaxed length thereof. In this way, the stowage requirements for the hose assembly are reduced, or alternately a hose having a substantially longer effective length can be used in a standard stowage box designed to accommodate a much smaller length conventional hose assembly.
In preferred forms, the hose assembly includes an inflatable elastomeric inner tube together with an exterior sheath formed of woven or braided material which in use restricts the radial expansion of the inner tube upon pressurization thereof, while allowing the tube to expand axially. The hose assemblies may have a deployed length of at least about 1.5 times the relaxed length thereof, and more preferably greater than about two times the relaxed length.